Angular 5节点js表示POST JSON Obj。 到Amazon Aws [外部API]（以前称为CORS问题）

Question

SOLVED, see my answer below

My server runs on localhost:3000

I develop on localhost:4200

I am creating something and trying to post it on an Amazon API

Angular side code:

sendSomething(something) {
    const body = JSON.stringify(something);
    // const headers = new Headers({'Content-Type': 'application/json'});
    const headers = new Headers({'Access-Control-Allow-Origin': '*'});
    return this.http.post('http://Amazon-API:port/send', body, {headers: headers})
      .map((response: Response) => response.json())
      .catch((error: Response) => {
        this.error.handleError(error.json());
        return Observable.throw(error.json());
      });
}

Server side:

//////////////app.js//////////////

app.use(cors());

app.use(function(req, res, next) {
  res.header("Access-Control-Allow-Origin", '*'); //<-- you can change this with a specific url like http://localhost:4200
  // res.header("Access-Control-Allow-Credentials", true);
  res.header('Access-Control-Allow-Methods', 'GET,PUT,POST,DELETE,OPTIONS');
  res.header("Access-Control-Allow-Headers", 'Origin,X-Requested-With,Content-Type,Accept,content-type,application/json');
  next();
});


app.use('http://Amazon-API:port', engineRoutes);




//////////////routes/engine.js//////////////

router.post('/send', engine_controller.send_something);



//////////////controllers/engine.controller.js//////////////

exports.send_something = function (req, res, next) {
  const somethingID = req.body.something;
  Something.findById(somethingID, function(err, something) {
    if (err) {
      res.status(404).json({
        title: 'Something not found',
        error: {message: 'Something went wrong'}
      });
    }
    console.log(something);
    if (something) {
      res.status(200).json({
        message: 'Something successfully sent',
        something: something
      });
    }
  })
};

I have tried posting to that API with cors, without cors and with the res.headers appended, and every other variation I could think of

I still get this error which I've seen so common around here, but still, their solutions don't seem to work for me. Still getting this error...

Failed to load http://Amazon-API:port/send : Response to preflight request doesn't pass access control check: No 'Access-Control-Allow-Origin' header is present on the requested resource. Origin ' http://localhost:4200 ' is therefore not allowed access. The response had HTTP status code 403.

That's from NETWORK tab:

Accept:*/*
Accept-Encoding:gzip, deflate
Accept-Language:he-IL,he;q=0.9,en-US;q=0.8,en;q=0.7
Access-Control-Request-Headers:access-control-allow-origin
Access-Control-Request-Method:POST
Connection:keep-alive
Host:Amazon-API:port
Origin:http://localhost:4200

Any kind of help would be so much appreciated

Answer 1

I see you added this code but I can't post comment yet, you may try to add this code before other routes

app.use(function (req, res, next) {
    res.setHeader('Access-Control-Allow-Origin', '*');
    res.setHeader('Access-Control-Allow-Headers', 'Origin, X-Requested-With, 
Content-Type, Accept');
    res.setHeader('Access-Control-Allow-Methods', 'POST, GET, PATCH, DELETE, 
OPTIONS');
    next();
});

Answer 2

Solved,

What I did was routing back to the server on the front:

sendSomething(something) {
  const body = JSON.stringify(something);
  const headers = new Headers({'Content-Type': 'application/json'});
  return this.http.post('http://localhost:3000/api/somethings/send-something', body, {headers: headers})
    .map((response: Response) => response.json())
    .catch((error: Response) => {
      this.error.handleError(error.json());
      return Observable.throw(error.json());
    });
}

And then accepting this route as it is on the back:

//////////////app.js//////////////////

app.use('/api/somethings/send-something', engineRoutes);



/////////////routes/engine.js/////////

router.post('/', engine_controller.send_something);

And most importantly, in the controller itself I used the newly downloaded request lib to send my json data to my external API:

////////////controlllers/engine.controller.js////////////

const request = require('request');

exports.send_something = function (req, res, next) {
  const SomethingID = req.body.something;
  Something.findById(SomethingID, function(err, something) {
    if (err) {
      res.status(404).json({
        title: 'Something not found',
        error: {message: 'Something went wrong'}
      });
    }
    request({
      url: app.get('amazon-API:port/method'),
      method: "POST",
      json: something
    }, function (error, response, body) {
      // console.log(error) <--- returns null or error
      // console.log(response.statusCode <--- returns 200 / 403 / w.e
      // console.log(body) <--- returns response pure html
      res.status(200).json({
        message: 'Something successfully sent',
        response: body,
        status: response.statusCode
      });
    });
  })
};

Now as a response I'm getting what the server which I posted to sends me back, which is exactly what I need.

Ultimately I figured my way thanks to many other questions posted here

So thank you SOF once again!